SDO 李乐平、张军、杨书红 国家天文台

SDO(Solar Dynamics Observatory) SDO was launched on Feb. 11, 2010 SDO is a sun-pointing semi-autonomous spacecraft that will allow nearly continuous observations of the Sun with a continuous science data downlink rate of 130 Megabits per second (Mbps). The spacecraft is 4.5 meters high and over 2 meters on each side, weighing a total of 3100 kg (fuel included). SDO's inclined geosynchronous orbit was chosen to allow continuous observations of the Sun and enable its exceptionally high data rate through the use of a single dedicated ground station.

Mission Orbit Overview The SDO geosynchronous orbit will result in two eclipse seasons with a variable daily eclipse each day – The two eclipse seasons will occur each year – During each eclipse season, SDO will move through the earth’s shadow- this shadow period will grow to a maximum of ~72 minutes per day, then subside accordingly as the earth-sun geometry moves out of the SDO eclipse season Eclipse season effects: – Instrument Interruption to SDO science collection Thermal impacts to instrument optical system due to eclipse – Power Temporary reduction or loss of power from solar arrays Battery sizing includes eclipse impact – Thermal S/C thermal design considerations due to bi-annual eclipses

Scientific goals 1. What mechanisms drive the quasi-periodic 11-year cycle of solar activity? 2. How is active region magnetic flux synthesized, concentrated, and dispersed across the solar surface? 3. How does magnetic reconnection on small scales reorganize the large-scale field topology and current systems and how significant is it in heating the corona and accelerating the solar wind? 4. Where do the observed variations in the Sun's EUV spectral irradiance arise, and how do they relate to the magnetic activity cycles? 5. What magnetic field configurations lead to the CMEs, filament eruptions, and flares that produce energetic particles and radiation? 6. Can the structure and dynamics of the solar wind near Earth be determined from the magnetic field configuration and atmospheric structure near the solar surface? 7. When will activity occur, and is it possible to make accurate and reliable forecasts of space weather and climate?

AIA is a key component to understanding the Sun and how it drives space weather AIA images the solar outer atmosphere: its science domain is shaded HMI measures the surface magnetic fields and the flows that distribute it EVE provides the variation of the spectral irradiance in the (E)UV

AIA ( Atmospheric Imaging Assembly ) Science objectives: – Energy input, storage and release; – Coronal heating and irradiance; – Transients; – Connection to geospace; – Coronal seismology. – CCD:4096*4096 – Spatial resolution: 0.6 ” pixels – Cadence:12 s

The wonderful challenge we have!

HMI (Helioseismic and Magnetic Imager) Observables: – Full disk Doppler velocity (45 seconds cadence, 4096x4096 CCD); – Full disk light-of-sight magnetograms (45 seconds cadence, 4096x4096 CCD); – Full disk continuum intensity; and – Full disk vector magnetograms (90 seconds res., 10 min cadence, 4096x4096 CCD).

Primary Science Objectives 1.Convection-zone dynamics and solar dynamo 2.Origin and evolution of sunspots, active regions and complexes of activity 3.Sources and drivers of solar activity and disturbances 4. Links between the internal processes and dynamics of the corona and heliosphere 5.Precursors of solar disturbances for space- weather forecasts

HMI Observables Continuum Line depth Line width Dopplergram LOS Magnetogram Vector magnetic field

Summary of instrument properties Filtergraph 4096x4096 full disk coverage 6173 FeI line 0.5” pixels, 1” optical resolution 76mA filter profiles – Generally spaced at 69mA Continuous coverage (>95%) Doppler and LOS at 45s cadence Full Stokes at 45s-135s cadence – About 2e-3 on (Q,U,V) in 135s – About 1e-3 in 12 minutes Uniform quality 95% temporal coverage – Eclipses are main problem

HMI Functional Specifications Summary

Vector Magnetic Field For AR1057 And Disambiguation (R. Centeno Eliot, J. Borrero, S. Tomczyk, K.D. Leka, G. Barnes, A. Crunch, T. Hoeksema, K. Hayashi, X. Sun) Line-of-sight field Azimuth Transverse field

Courtesy HMI Team and K. Hayashi Vector Magnetic Field from Mar 29 Sunspot (K. Hayashi, R. Centeno Eliot, et al.)

EVE ( Extreme Ultraviolet Variablity Experiment ) Science objectives: – Specify the solar EUV spectral irradiance and its variability on multiple time scales – Advance current understanding of how and why the solar EUV spectral irradiance varies – Improve the capability to predict the EUV spectral irradiance variability – Understand the response of the geospace environment to variations in the solar EUV spectral irradiance and the impact on human endeavors.

19 EVE Overview E xtreme ultraviolet V ariability E xperiment ( EVE ) The Key Components of EVE  EVE Optical Package (EOP) Multiple EUV Grating Spectrograph (MEGS)  MEGS A + SAM (Solar Aspect Monitor)  MEGS B + P (Photometer Channel) EUV Spectrophotometer (ESP)  EVE Electrical Box (EEB) EVE processor CCD power converter/regulator ESP power converters ESP MEGS B/P MEGS A SAM EOP EEB EVE purpose: To measure and model the solar EUV irradiance variations due to flares (seconds), solar rotation (days), and solar cycle (years) EVE Metrics PowerAverage (28V) 43.9 watts Mass54.2 kg Data Rate2 Kbps (engineering) 7 Mbps (science) Wave Length Range0.1 nm – 105 nm Dimensions (EVE Envelope)~39”L x 24”W x14”H

Eparvier - 20 How does EVE measure the EUV? Multiple EUV Grating Spectrograph (MEGS) – At 0.1 nm resolution MEGS-A: 5-37 nm MEGS-B: nm – At 1 nm resolution MEGS-SAM: 0-7 nm – At 10 nm resolution 122 nm – Ly-  Proxy for other H I emissions at nm and He I emissions at nm EUV Spectrophotometer (ESP) – At 4 nm resolution 17.5, 25.6, 30.4, 36 nm – At 7 nm resolution 0-7 nm (zeroth order) In-flight calibrations from ESP and MEGS-P on daily basis and also annual calibration rocket flights  nm

SDO 工作 1 、冕洞边界上磁重联的 SDO 观测 ( 杨书红、张军、李婷、刘扬， 2011, ApJ, 732, L7) SDO Observations of Magnetic Reconnection at Coronal Hole Boundaries 2 、宁静太阳中无处不在的旋转网络场和远紫外龙卷风（张军、刘 洋， 2011, ApJL ， under review ） Ubiquitous rotating network fields and EUV cyclones in the quiet Sun 3 、暗条倒钩（ barbs ）的演化（李乐平、张军， 2011, Solar Physics, under review ） The evolution of filament barbs

Thank You!